Federated Farmers has given police names of people involved in the 1080 debate to help with their investigation into the infant formula threat.
Police revealed yesterday they had spent more than three months investigating a threat to poison infant and other milk formula with the poison unless 1080 drops stopped by the end of March.
Federated Farmers president William Rolleston said names from various sources, including previous correspondence and historical publications, had been given to police.
However, he said he did not know who would be behind the blackmail and he had not received any threatening letters before.
Dr Rolleston said he had advised members and provincial presidents to be vigilant and to make sure milk supplies were secure.
"Farmers in general are outraged and angry, as the rest of New Zealand," he said.
"I'd be surprised if any farmer would be in support of this action."
He said he was not worried about any fallout in overseas markets, and any pain would be short-term as the industry had a reputation of transparency and trust.
"We're in a position that people trust us. We need to be in that position of trust and this is part of building that trust."
"I think the long-term international outcome will be positive, not negative," he said.